Kitchen extensions

When weighing up the cost of a kitchen extension, you’ll need to factor in the cost of the build itself, and then the kitchen fixtures and fittings. On average, buying a new kitchen costs between £5,000 and £30,000 (but it could be a lot more if you go for something bespoke). As for the build, average prices at the moment are between £2,200-£3,500 per m² excluding VAT. If you live in London or the surrounding areas, it’ll be on the higher end.

Kitchen extensions can be different shapes, sizes and complexities, which means there’s not a one-size-fits-all timeline. But on average, a home extension in the UK takes between 7 and 12 months from start to finish. That includes the time spent working with an architect on design, getting planning permission, having detailed technical drawings done, choosing who does your construction, and then the build itself.

In short, it’s very unlikely that you’d be able to build a kitchen extension for £20,000. Unless you were doing a large portion of the construction work yourself, of course, or you knew how to source a very cheap kitchen. Average construction costs in 2025 are around £2,200-£3,500 per m², and kitchens typically range from £5,000 to £30,000, which probably gives you a sense of why it’s unlikely to come in under £20k.

Once you’ve finished researching your kitchen extension and have some idea of what you like and don’t like, Resi can get involved to make it all happen. First, we’ll carry out a survey of your home using 3D scanning technology, ready for the design phase. Then, you’ll work with one of our architects to design a new layout that works for you.

Our in-house team of planning experts (with an approval rate of over 90%) will then make your planning permission application and handle any back-and-forths there. And once that’s been approved, our building regulations experts will prepare your full technical drawings. If needed, Resi can also introduce you to trusted specialists like structural engineers, drainage surveyors, or party wall surveyors.

If you’d like help choosing your builder, Resi’s Connect service can introduce you to some vetted, local builders for quotes, which we’ll help you weigh up.

Then it’s on to the building work, picking your new kitchen, and before you know it, you’ll be cooking your first meal on shiny new worktops.

Whether or not you can keep your old kitchen during the build of your new one totally depends on your circumstances. For smaller side-return or rear extensions, you might be able to keep a functional corner of your kitchen or a temporary setup. With larger projects, particularly orangery kitchens or wraparound extensions, your kitchen will likely be out of action for weeks while walls, floors, and utilities are worked on. Planning ahead and setting up a temporary kitchen (think: air fryer) in another room can make life much easier.

There are so many factors that can influence how much value an extension can add to your home. Things like where you live, how big a space you’ve added, and what the new rooms are used for. As a general estimate, though, extending your kitchen could increase your property’s value by around 10-15%. For a better idea of how much value you could add to your house, try Resi’s free extension valuation calculator.